1. Field of Invention
The present invention relates to X-ray equipment and, more particularly, is directed towards a moving source of X-rays.
2. Description of the Prior Art
X-rays computed tomography for medical diagnostic processes involves the use of a moving source of X-rays for producing either a single cross-sectional density profile of an irradiated subject under diagnosis or a two-dimensional density profile from a spatially separated sequence of such cross-sectional profiles. Since it is necessary to irradiate the subject from a large number of different directions in a common cross-sectional plane, the X-ray source encircles or scans the subject for at least one half an orbit and, in many instances, for an entire orbit.
Prior art approaches for moving the X-ray source involve the direct mechanical transport of a standard hard vacuum X-ray generating tube and its associated high voltage power cables. In order to eliminate blurring of the density profile due to subject motion, such as respiration and heart beat, it is necessary that the total scan time is made to be substantially less than the time intervals characteristic of such subject motions. Due to the difficulties associated with faster mechanical transport of the X-ray tube, and such associated problems as coiling and uncoiling of high voltage cables, attempts at increased scan rates have been met with qualified acceptance. Systems of the type shown in U.S. Pat. No. 3,106,640, which provide a moving source of X-rays by deflecting a rotating beam onto a circular target, have been introduced with varying degrees of success.